2.8 Basic Unwrap Problem?
In 2.8 where is new View mode in uv/image editor.
In this mode where is no UVs or mask or painting tools are display. To edit UV you need to switch to UV edit mode:

 

New View mode is good for viewing image for reference.

Note, that where is new UV editing workspace with uv/image editor with uv edit mode by default:



Tool 'Select Box' not found for space 'IMAGE_EDITOR' it is just a warning don't pay attention to it.